John Pazmino
 NYSkies Astronomy Inc
 2002 December 21
[Dates are Julian Universal Time. Dates may differ slightly from 
other calcs due to algorithms and definitions]
    year     date    event
    -------  ------  --------------------
    early birth events
    7BC, -6  May 29  Jupiter-Saturn conjunction
             Jul  7  Saturn western station
             Jul 17  Jupiter western station
             Sep 14  Saturn opposition
             Sep 15  Jupiter opposition
             Sep 30  Jupiter Saturn conjunction
             Nov 12  Jupiter eastern station
             Nov 20  Saturn eastern station
             Dec 12  Jupiter-Saturn conjunction
    6BC, -5  Feb 20  Moon-Mars conjunction
                     Moon-Jupiter conjunction
                     Moon-Saturn conjunction
                     Moon-Mars-Jupiter-Saturn convention
                     Mars-Saturn conjunction
             Mar  4  Mars-Jupiter conjunction
             Mar xx  nova in Aquila-Capricornus
             Apr 17  Moon-Jupiter occultation
             Jul xx  nova in Cygnus [these MAY be rally a comet moving 
                     from Capricornus to Cygnus, lasting 70 days, OR 
                     nova misplaced but still lasting 70 days] 
             Aug 22  Jupiter western station
             Oct 21  Jupiter opposition  
             Nov 16  Jupiter eastern station
    Herodus's events
    4BC, -3  Mar 13  partial lunar eclipse
    1BC,  0  Jan 10  total lunar eclipse
    1BC   0  Dec 29  partial lunar eclipse  
    late birth events
    4BC, -3  May 18  Venus-Mars conjunction
             May 24  Venus-Jupiter conjunction
             May 24  Venus-Mars-Jupiter convention    
             May 31  Mars-Jupiter conjunction
    3BC, -2  Aug 11  Moon-Venus-Jupiter convention 
             Aug 12  Venus-Jupiter conjunction
             Sep 13  Jupiter-Regulus conjunction
             Nov 27  Jupiter western station
    2BC, -1  Jan 26  Jupiter opposition
             Feb 18  Jupiter=Regulus conjunction
             Mar 29  Jupiter eastern station
             May  7  Jupiter-Regulus conjunction
             Jun 17  Jupiter-Venus consolidation
             Aug 31  Moon-Venus-Mars-Jupiter convention
    modern events (Gregorian dates)
    1779AD   Nov  9  Mira brightest maximum of 1.3 magnitude 
    1972AD   xxx xx  Enif flareup to 0.9 magnitude
    1980AD   Dec 31  Jupiter-Saturn conjunction
    1981AD   Jan  2  JUpiter western station
             Jna 18  Saturn western station
             Jan 24  Jupiter western station
             Mar  4  Jupiter-Saturn conjunction
             Mar 26  Jupiter opposition
             Mar 27  Saturn opposition
             May 27  Jupiter eastern station
             Jun  5  Saturn eastern station
             Jul 24  Jupiter-Saturn conjunction
    1994AD   Jul xx  Jupiter-SL9 collision
    1998AD   Apr 23  Moon-Jupiter occultation, with Venus
             Apr 23  Moon-Venus occultation, with Jupiter
    2000AD   Feb xx  Dschubba flareup to 1.8 magnitude
[Not exhaustive, but I touched the important points] 
    Years are numbers in the BC era in two ways. The historical or 
chronological method starts with '1BC' for the year preceding 1AD. The 
numbering continues backwards into the past from there. There is NO 
year number '0'. 
    The astronomical or algebraic method counts with a year '0' and 
past years are negative numbers. Lo here the timeline for comparison. 
      -7    -6    -5    -4    -3    -2    -1     0     1     2 
      8BC   7BC   6BC   5BC   4BC   3BC   2BC   1BC   1AD   2AD 
    Note that the 'BC' year is one GREATER in absolute value than the 
'minus' year. You MUST understand how your planetarium program treats 
years in the BC era to set it correctly for Christmas Star 
    I don't know, and can't find any one who knows, why AD is Latin 
and BC is English. I have seen 'AC' for 'ante Christo' for BC years. 
    The calendar in force across the BC/AD period was the Julian, not 
Gregorian, calendar. The contemporary calendar was a bit out of joint 
from political tampering and lack of modern concepts of 'history'. All 
dates are now established by a copasetic Julian calendar. 
    For studies before the Julian calendar (about -45 or 46BC) we 
prolong the Julian calendar backwards, even tho the 'date' is then 
entirely fictitious. That's why you can read of some Japanese eclipse 
on, made up, 1234BC January 8, when there simply was no such a date in 
existence so far long ago. 
    The days of the week are generally missed out in the BC era for 
astronomy purposes. However, the week cycles thru the seven days 
without interruption or shuffling regardless of what happens to the 
calendar date. 
    Planetarium programs MUST have longterm dynamics for the planetary 
motions and precession. Using a program with 'trolley track' orbits 
and a simple precession will yield erroneous simulations. Some 
programs specify the range of valid years; HNSky, for instance, will 
NOT work for years before 1750. Others don't trap invalid dates but 
will then display all wrong skies. 
    The program MUST be fed contemporary comet orbit elements. You can 
NOT just change the perihelion date of a modern orbit. 
    SkyMap, Starry Night, Dance, SkyGlobe, Expert Astronomer are 
examples of good planetarium programs. 
    Jerusalem is at latitude 31 degrees north, longitude 48 degrees 
east, rounded. A shift eastward in longitude only affects the hour of 
a sky display. You may pick from your planetarium's city list any 
place in Israel, Jordan, Iraq, or Iran. These modern countries are in 
the path presumably taken by the Magi, who likely (but hardly 
certainly!) came from either Babylonia or Persia. 
    The delta-T correction, the offset of Universal Time from the 
Atomic Time, may be ignored. Your planetarium may work with a lookup 
value or may be lack a delta-T feature. 
    The one and only account of the Star is in book of Matthew. There 
is no other independent record of the Star, only commentary based on 
Matthew. Matthew does not say anything about: 
  the brilliance of the Star 
  the size, shape, changes of the Star 
  which segment of the day the Star was seen 
  how many Magi came to Bethlehem 
  where specificly the Magi came from 
  the time frame for the Magi's trip 
    Any assertions about these features comes from external 
considerations, not as yet certainly founded in history. 
    The Star could be a single celestial event or a series of events. 
It may be an interpretation of some reproducible predictable event, or 
one which was unpredictable and now nonreproducible. 
    On the other hand the Star could be a truly other-worldly 
apparition or a total fabrication. 
    Astrology may be a weak feature in the Christmas Star story 
because the magi were basing their trip on the Jewish scriptures and 
Jewish faith. Faithful Jews did not practice astrology 
    The magi, coming from (presumably) a nonJewish territory still 
practicing astrology, may have blended Jewish teachings with 
astrology. More over, there was no monolithic 'astrology' at that 
time, but a variety of practices, each with its own lore and methods 
    Alignments of planets would have been closely, if not accurately, 
predictable at that time. Almanacs were good enough from Babylonian 
and Greek astronomy. The magi were not seeing, among the planets, 
unknowable or unpredictable events. They may have studied the planets 
to improve their almanacs or to satisfy themselfs that the almanacs 
were working. 
    The date of the Nativity is STILL very much unsettled. There are 
two schools, the 'early birth' and 'late birth'. The former sets the 
Nativity in 6BC (+/- 1 year). The latter puts it in 2BC (+/- 1 year). 
The cause is the dispute over when Herodus died. 
    Matthew says the Nativity occurred during Herodus's reign, which 
ended in EITHER 4BC or 1NC. The dispute is about which of two lunar 
eclipses immediately preceded his death. 
    The present AD count of year wasn't started until about 540AD, by 
which time memory and records may have been lost. This period was the 
initial throes of the Dark Ages, following the collapse of the Roman 
empire in the west. It was also the beginning of the Byzantine era in 
the east. 
    As careful as the counting was done, errors easily could have 
slipped in. There was provision for a zero year and, in fact, there was 
no notion to extend the count before the Nativity. 
    It REALLY helps to know Latin, to understand documents, coins, 
monuments, and the like in reading up on the Star of Bethlehem.